Sanken Electric Co., Ltd.

Kazushige Hirata

Toru Ashikaga

Kengo Kimura

Toshihiro Nakano

Mizuki Utsuno

Toyotomo Morita

An LED driving apparatus converts AC input power into predetermined DC output power and supplies the DC output power to an LED load. The LED driving apparatus includes a switching element Qto be turned on and off, a ripple current reducerthat is connected in series with the LED load and reduces current ripples of the LED load, and a controller CNT that turns on and off the switching element according to a feedback voltage taken from a connection point of the LED load and ripple current reducer, thereby controlling the DC output power to a predetermined value.

LED driving apparatus and LED lighting apparatus

A discharge lamp lighting device is provided to comprise tube current detecting circuitstofor outputting detection signals Vto Vof tube currents Ito Iflowing through each discharge lamptofrom an inverterconnected to DC power sourcevia a plurality of transformersto, a maximum detectorfor detecting a maximum value Vof detected signals Vto Vfrom current detectorto, a minimum detectorfor detecting a minimum value Vof detected signals Vto Vfrom current detectorto, a comparison circuitfor computing one or plural values of sum, difference, product and quotient between maximum value Vfrom maximum detectorand minimum value Vfrom minimum detectorto generate a cease signal Vwhen the computed value exceeds a given value, and a control circuitfor halting operation of inverterwhen comparison circuitgenerates cease signal V. The device can reliably detect arc discharge resulted from electric connection failure in discharge lamp or lamps by the computed values from comparison circuitto positively protect discharge lamps from overheating by arc discharge at a bad connection location.

Discharge lamp lighting device

A luminescent lamp lighting device includes a plurality of switch circuitseach connected to each of luminescent lampsin series under one-to-one correspondence, a plurality of optical coupling circuitseach connected to each of the switch circuits under one-to-one correspondence to turn on/off the switch circuits and a plurality of current detecting circuitseach connected to each of the luminescent lamps in series under one-to-one correspondence to detect currents flowing the luminescent lamps. The device determines whether the luminescent lamps are turned on or not, based on the currents detected by the current detecting circuits and controls the optical coupling circuits based on the determination result so as to allow all of the luminescent lamps but a luminescent lamp requiring a highest lighting voltage to be turned on in order of low lighting voltage, next allow the lighted luminescent lamps to be turned lighted off, and allow all of the remaining luminescent lamps to be turned on again after turning on the luminescent lamp requiring the highest lighting voltage.

Growing community of inventors

Niiza, Japan

Kazushige Hirata